JPS61217009A - Plastic optical fiber - Google Patents

Abstract

PURPOSE:To obtain an optical fiber which has superior heat shrinkage and inflection resistance by forming the protection layer of the optical fiber to specific thickness by using an organic polymer which has specific characteristics. CONSTITUTION:The optical fiber is constituted by covering a bulk optical fiber (optical fiber core) 4 consisting of a core material layer (core) 1, a sheath material layer (clad) 2, and the protection layer 3 with a primary coating layer 5 and a secondary coating layer 6. Then, the protection layer 3 is formed of the organic polymer with a >=5X10<2>kg/cm<2> flexural Young's modulus to a <=250mum thickness. Consequently, problems of irregularity in structure, damage up to coating work, and a failure in selecting a coating material with higher heat resistance which accompanies conventional plastic optical fibers are solved and characteristics of heat shrinkage, inflection resistance, optical transmission loss, etc., are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plastic optical fiber, and more particularly to a plastic optical fiber that can be used for an optical fiber core or a single fiber cable.

[Conventional technology]

Conventionally, inorganic glass optical fibers have been known as optical fibers, which have excellent optical transmission properties over a wide range of wavelengths, but they are difficult to process, have low bending stress, are bulky, and are expensive. Since then, optical fibers based on plastic have been developed and put into practical use.

This plastic optical fiber is made of polymethyl methacrylate (PMMA), which has a large refractive index and good light transmittance.
), polystyrene (ps), polycar? Ne) (P
A core material layer (core) whose base material is a polymer such as C), and a sheath material layer (cladding) whose base material is a transparent polymer such as a fluorine-containing polymer with a smaller layer liquid ratio than this. is the basic structural unit. The product forms of these core-clad type optical fibers (optical fiber strands) include bulk fibers such as optical fiber strands, optical fiber cores coated with a functional protective layer, and optical fiber strands. Cover the wire (
There are optical fiber cords coated with a jacket material), and optical fiber cables that combine bulk fibers or aggregate fibers that are aggregates of bulk fibers with tension members and the like. .

Conventionally, it has been proposed to use heat-resistant and high-strength engineering plastics such as polycargenate, polyamide, and polyacetal as the base material for the protective layer of the optical fiber core wire. When forming a protective layer using a material, the thickness is generally more than 100N and usually about 500μm or more, which causes structural irregularities such as distortion in the optical fiber and increases optical transmission loss. This method has the disadvantage that it causes inconvenience in connecting fibers or fibers together.

On the other hand, for example, when an optical fiber shaped by core/clad composite spinning is coated and then coded or cabled, the optical fiber may be cracked or damaged during the coating process. There was an inconvenience that an accident could occur.

In addition, if a fluorine-containing polymer or the like, which has relatively poor heat resistance, is used as the base material of the cladding, there is an inconvenience that a coating material with higher heat resistance cannot be selected and coated. [Problems to be solved] The present invention solves the problems of structural irregularities such as distortion associated with the conventional plastic optical fiber mentioned above, damage during the coating process of the optical fiber wire, and a coating material with higher heat resistance. This was done to solve the problem of not being able to use it selectively.

[Means for solving problems]

That is, the plastic optical fiber of the present invention, which was discovered as a means to solve the above problems, is a plastic optical fiber having a primary coating and a secondary coating on a bulk fiber consisting of a core material layer, a sheath material layer, and a protective layer. The protective layer is made of an organic polymer having a flexural modulus of 5 x 102 IK9/-2 or more, and has a thickness of 250 microns or less.

〔Example〕

EXAMPLES The present invention will be described in detail below with reference to Examples.

1 to 7 are cross-sectional views of an optical core 4 for explaining configuration examples of the plastic optical fiber of the present invention.

FIG. 1 shows a structure in which Glug fiber (optical fiber core) 4 is composed of a core material layer (core) 1, a sheath material layer (cladding) 2, and a protective layer 3, and a primary coating layer 5 and a secondary coating layer. This is an optical fiber coated with 6, and with such a configuration it can be used as it is as an optical fiber core or an optical fiber cord.

If the same elements as in the example of Fig. 1 are represented by the same symbols, the second
The examples shown in Figures 1 and 3 are optical fibers in which tension members 7, 7, etc. are combined with the fiber having the configuration shown in Figure 1.
Tension member 7.7...c Arranged in the primary coating layer as in the example in Fig. 2, or disposed close to the outer peripheral surface of the primary coating layer as in the example in Fig. 3. The shape, location, number, etc. of the tension members are arbitrarily selected and arranged.

The same elements as in FIG. 1 are represented by the same reference numerals.The examples in FIGS. 4 and 5 are optical fibers in which a metal coating layer for moisture proofing is combined with the fiber having the configuration in FIG. In the example shown in FIG. 4, a covering layer 8 formed by wrapping with a thin metal plate (foil) or metal plating is provided along the outer peripheral surface of the primary covering layer 5, and in the example shown in FIG. A coating layer 9 made of a metal tube or the like is provided along the outer peripheral surface of the tube. Metals used for metal coating include aluminum, stainless steel,
Examples include copper, zinc, tin, etc.

In the example shown in FIG. 6, a plurality of optical fibers each having a core 1', a cladding 2', and a protective layer 3' shaped with their axes aligned are connected to a primary coating layer 5' and a secondary coating layer 6 according to the present invention. It is an optical fiber that is coated with .

The example in FIG. 7 shows an optical fiber 10 having the same configuration as the example in FIG.
．． 10... is exemplified as an example of an optical fiber cable configured by bundling a plurality of cables and combining them with a tension member 11 and the like.

As the base material for the cores 1, 1', non-grade transparent polymers are suitable, such as homopolymers or copolymers of methyl methacrylate (at least 70% by weight of the starting monomers are methyl methacrylate, 30% by weight). % or less is preferably a monomer copolymerizable with methyl methacrylate. Examples of monomers copolymerizable with methyl methacrylate include vinyl monomers such as methyl acrylate and ethyl acrylate. Copolymers of methacrylic acid esters such as cyclohexyl acid, t-butyl methacrylate, isogernyl methacrylate, adamantyl methacrylate, benzyl methacrylate, phenyl methacrylate, and 7-tyl methacrylate, and 7-tamine copolymerizable with these. ,
Polycarbonate, polystyrene, styrene-methacrylic acid ester copolymers, deuterated polymers in which all or some of the hydrogen atoms of these polymers are replaced with deuterium atoms, etc. can be used, and of course, other transparent Polymers, transparent polymers, and transparent blends can also be used.

As the base material for the claddings 2 and 2', a substantially transparent polymer having a refractive index smaller than the refractive index of the base material for the core 1 by 01 or more is used; It is preferable to select from those with a difference in the range of 0.01 to 0.15. There is no particular restriction on the type of polymer constituting the cladding, and conventionally known polymers may be used. For example, when the core is a homopolymer or copolymer of methyl methacrylate, Japanese Patent Publication No. 43-8978, Special Publication No. 56-8321,
Polymerized esters consisting of methacrylic acid and fluorinated alcohols as disclosed in Japanese Patent Publication No. 56-8322, Japanese Patent Publication No. 56-8323, Japanese Patent Publication No. 53-60243, etc. can be used. It is. Further, when polycarbonate or polystyrene is used as the core, for example, polymethyl methacrylate can be used as the cladding. Other specific examples of cladding include, for example, Japanese Patent Publication No. 43-8978 or Japanese Patent Publication No. 53-422.
Vinylidene fluoride-hexafluoroglopyrene-based copolymers, methacrylic acid ester-based polymers other than the polymethyl methacrylate, Methylpentene-based polymers can also be used as cladding.

The protective layers 3, 3' according to the present invention have a flexural modulus of 5×10
2kl? /crn or more, preferably I x 10' units/crn or more, organic polymers that meet such conditions include, for example, polyamide, polyester elastomer, polycarbonate, nylon elastomer, High-density polyethylene (HDPE), linear low-density polyethylene (L-LDPE), poly-4-methylpentene-1, polyvinylidene sulfide, ionomer, ethylene-ethyl acrylate-4-copoly-r-(EEA)
), polymethyl methacrylate, nylon resin, and other synthetic resins.

Primary coating layer 5, 5' and secondary coating layer 6.6 according to the present invention
' can be provided using any combination of organic polymers as a base material, but as an example of the combination of organic polymers, the primary coating layers 5 and 5' can be formed of an organic polymer having a relatively low flexural modulus. The secondary coating layer 6.6' is composed of an organic polymer having a relatively high bending modulus to maintain the mechanical strength of the fiber.
Further, it is possible to provide the effect of protecting the fiber from external force.

As a method for producing the plastic optical fiber of the present invention, a method for forming the bulk fiber and coating layer is generally performed by appropriately selecting spinning or composite spinning and coating processing by extrusion, coating, etc. , and so on,
The core, cladding, and protective layer are formed using a composite spinning method, and the respective base polymers are blended in a molten state using a special nozzle and then discharged and shaped, and then formed onto the Nonoluku fiber that is shaped in this way. A method in which the primary coating layer and the secondary coating layer are sequentially applied is preferred because the effects of the present invention are noticeable. In addition, in order to arrange tensile strength and strength on the fiber, a method is generally used in which layers are formed by intervening them during spinning or coating processing, and in order to form a metal plating layer, A metal plating layer of desired thickness can be formed on the resin surface by conventional methods such as chemical plating and vacuum deposition.

The diameter and thickness of each constituent layer of the plastic optical fiber of the present invention can be determined as appropriate depending on the purpose of use, but for example, in the case of the fiber shown in FIG.
00 μm, cladding thickness 1-300 μm, primary coating layer thickness 3-500 μm, secondary coating layer thickness 100-50 μm
It is said to be about 00 μm. Further, in the present invention, the thickness of the protective layer needs to be 250 μm or less. Thickness is 2
If the number exceeds 50, structural irregularities such as distortion are likely to occur particularly in the core and cladding portions, which is not preferable. Especially the core?
Bulk fiber diameter including rad and protective layer is 250
~1500 μm, the outer diameter of the fiber is 500~30
It is preferable to set it to about 00 males.

Specific examples are given below, but the embodiments of the present invention are not limited thereto.

Example 1 100 parts of methyl dimethacrylate and t-butyl mercaptan were produced by continuous bulk polymerization using a volatile matter separator consisting of a reaction tank equipped with a S-Arirarimen type stirrer and a twin-screw one-vent type extruder. A monomer mixture consisting of 0.40 parts of di-tert-butyl/0.00017 parts of mother oxide was reacted at a polymerization temperature of 155°C and an average residence time of 4.0 hours, and then the temperature was adjusted to a temperature similar to vent extrusion at a pend section 260. °C,
The volatile part was separated at 250°C in the extrusion part and 4 mHg in the pent part, and the core component polymer (CPMMA) was 250°C.
It was supplied to a core-sheath-protective layer three-component composite spinning head at 250° C. through a gear pump section maintained at a temperature of 250° C. (flexural modulus of core component = 3×10′/crn2).

On the other hand, methacrylic acid chloride and 2.2,3,3.3-
2,2,3,3,3-pentafluoropropyl methacrylate 10
A sheath component polymer (5FM) with a refractive index of 1.417 was obtained by polymerizing 0 part of methacrylic acid and 1 part of methacrylic acid in the presence of a small amount of n-octyl mercaptan using azobisin butyronitrile as a catalyst.
I got it. This sheath component polymer was supplied to a composite spinning head at 250°C via a gear pump in a scree melt extruder set at 220°C.

In addition, as a polymer for the protective layer, an ionomer (ε1 = 2
．． 5 x 10 kg 7 cm) was melted and kneaded.
The s3-r- was fed to a composite spinning head at 250°C via a gear pump in a SKU IJ-melt extruder set at 250°C.

The melted polymers of the core material layer, sheath material layer and protective layer that were supplied at the same time were heated to 250°C using a spinneret (nozzle diameter: 5 φ).
1. After cooling and solidifying, it was taken out at a speed of 31 mIn, rolled and rolled, the core material had a diameter of 900 μm, and the sheath material had a thickness of 5 μm.
A fiber with a protective layer thickness of 45 μm was shaped.

Next, polycargene (PC) was applied as a primary coating material onto this fiber using a crosshead cable processing method.
) and coated with 6.12 nylon as a secondary coating material to obtain an optical fiber with an outer diameter of 2.2 m.

The thermal shrinkage rate, cyclic bendability, and optical transmission loss of the optical fiber thus obtained were evaluated using the following evaluation methods. The results are shown in Table 1.

〔Evaluation methods〕

(1) Heat shrinkage rate 1o by the method shown in Japanese Patent Application No. 59-103664.

The value at °C was determined.

(2) Repeat bendable optical fiber is attached to a mandrel with a diameter 5 times the fiber diameter.
The sample was bent at 0°C and the number of bends at which the light intensity retention rate reached 50% was read.

(3) Optical transmission loss The method disclosed in JP-A-58-7602 was used.

The measurement wavelength is 650 nm. Light with a numerical aperture of 0.6 was used as the incident light on the optical fiber.

Examples 2 to 17, Comparative Examples 1 to 7 In Examples 2 to 17 and Comparative Examples 1 to 7, optical fibers were manufactured using the same equipment and the same method as in the Examples.
The thermal shrinkage rate, cyclic flexibility, and transmission loss were measured using the same evaluation method as in Example 1, and the results are shown in Table 1.

As shown in Comparative Example 1, if the bulk fiber does not have a protective layer with a bending elastic modulus of 5 x 10 kg/m or more and a thickness of 250 μm or less, and is directly coated with the primary coating and secondary coating, the bending resistance will be extremely weak. I understand.

As shown in Comparative Example 2, the bending elastic modulus of the protective layer is 5X1
When it is less than 0 J/cm, the thermal shrinkage rate becomes large.

As shown in Comparative Examples 3 to 6, the thickness of the protective layer is 250 μm
It can be seen that when the value exceeds , the crystallization strain of the protective layer affects the phi and the transmission loss increases.

〔Effect of the invention〕

According to the present invention, problems associated with conventional plastic optical fibers such as structural irregularity, damage during coating processing, and inability to select a coating material with high heat resistance, can be solved.
It is possible to provide a plastic optical fiber that solves these problems and has excellent properties such as heat shrinkability, bending resistance, and optical transmission loss.

[Brief explanation of the drawing]

1 to 7 are cross-sectional views of optical fibers for explaining configuration examples of the plastic optical fiber 4 of the present invention. 1.1'...Core, 2.2'...Clad, 3,3
'...Protective layer, 5,5'...Primary coating layer, 6,6'
...Secondary coating layer.

Claims (1)

[Claims] A plastic optical fiber having a primary coating and a secondary coating on a bulk fiber consisting of a core material layer, a sheath material layer and a protective layer, wherein the protective layer has a flexural modulus of 5 x 10^2 Kg.
1. A plastic optical fiber characterized by having a layer having a thickness of 250 μm or less and made of an organic polymer with a thickness of /cm^2 or more.